Lubricant



atente .lnly 27, 1943 LUBRICANT Raymond Renter, Medford Lakes, N. 3., assignor to The Atlantic Refining Company, Philadelphia, Pa, a corporation of Pennsylvania No Drawing.

l '7 Giaims.

This invention relates to the treatment of ydrocarbon products such as mineral oils to improve their characteristics, and particularly to the addition of petroleum lubricating oils of certain materials which improve "their ability to resist the deteriorating effect of oxidation and their ability to lubricate bearing surfaces which are subjected to extreme pressures such as are now commonly encountered in the newer types of machinery.

Moderately refined oils,'such as motor oils and other moderately refined lubricating oils and moderately refined turbine oils normally used under conditions of exposure to oxidation in the presence of metals, oxidize, giving rise to sludge and/or acidic oxidation products frequently corrosive to the metals which they encounter in use, as for example bearing metals in automotive use, and copper and copper alloys in turbine use. It has now been found that stabilization of these oils against such oxidation eiiects may be conveniently accomplished by addition to the oils of certain materials which substantially retard the oxidation of the oils, whether or not metal is present, and which apparently have the ability to inhibit the catalytic effect of metals in promoting oxidation reactions and thus prevent the formation of sludge and/or acidic constituents and the like under normal conditions of use.

Recent changes in automotive engine design, tending toward higher bearing pressures, higher rotative speeds, higher engin temperatures, and the like, have occasioned departure from the use of the usual bearing metals such as babbitt. The newer bearing metals are of different nature, than those less recently developed and while harden-are in general more susceptible to destructive agencies of a corrosive nature. Typical of these newer bearings are those composed of a cadmium-silver alloy supported upon a steel back, which are now widely installed in certain makes of automobiles. Others of these relatively new bearing metals which may be mentioned are copper-lead alloys, copper-lead-tin alloys, cadmium-nickel alloys, cadmium-zinc alloys, cadmium-zinc alloys modified by the presence of lead, antimony, or both, and a general class of 'alloys consisting mainly of lead and hardened with calcium, barium, potassium, antimony, and the like, known generically as high lead babbitts. v 1

These changes in engine design have been concurrent with marked advances in methods of refining lubricant oils for'automotive use. The demand for oils having lesser changm in viscosity Application February 20, 1940, Serial No. 319,839

with temperature change; i. e., higher viscosity index (frequently designated as V. 1.), has been met by refining lubricants intended for motor oils by certain solvent refining or solvent extraction processes, wherein advantage is taken of the selective solvent power for hydrocarbons of various types-which is possessed by certain liquid reagents, for example, dichlorodiethylether, cresylic acid, phenol, chloraniline, chlorophenol, phenetidine, benzyl alcohol, nitrobenzene, benzonitrlle, furfural, aniline, benzyl acetate, liquid sulphur dioxide, mixtures of liquid sulphur dioxide or aniline with benzol, and the like. Those solvent refining processes are designed to concentrate in the desired lubricant fraction those compounds of a parafiinic" nature possessed of the ability to suffer only a small change of viscosity with change of temperature, and to reject the compounds of naphthenic nature whichdo suffer such change of viscosity to a marked degree. These refining processes have provided a supply of oil of quite desirable general characteristics, definitely far superior to any oil previously produced from mixed base or asphaltic crudes, and superior to a like, though lesser, degree over oils previously produced from paramn base crudes.

It has been found that the solvent refined motor oils referred to above are definitely corrosive to the newer bearing metals referred to above under extreme conditions of automotive use, due to oxidation durin use, sometimes resulting in bearing failure after only a few thousand miles of driving. Difficulties are frequently encountered due to bearing corrosion in automotive equipment operated at sustained high speeds of the order of 60 to M. P. H., or under other conditions conducive to high crankcase temperatures of the .order of 275 F. or higher. It is further known that the same reaction, viz., corrosion of alloy bearing metals such as cadmium-silver, also occurs in good paraflinic base oils which have not been subjected to solvent refining. The higher the V. I. of the lubricating oil, the. more pronounced is the tendency to corrosion of the kind referred to above. Generally speaking, the problem is encountered in oils havinga. V. I. of or higher, particularly at elevated temperatures of engine operation.

' Furthermore, the present trend in automotive designtoward lower body styles, rapid acceleration, and the use of hypoid gears has increased the unitloadings on rear axles. In some cases the unit pressures encountered become great enough to rupture the oil film, of ordinary mineral oil lubricants, with consequent metal to metal contact. In other lines of power transmission and the like, there is a similar tendency toward the use of high unit pressures of a degree which are near or beyond the limit at which mineral oils, alone, will maintain effective lubrication. This invention is therefore specifically concerned with the production of lubricants capable of sulphur dissolved in mineral oil, sulphurized vegetable or animal oils, chlorinated compounds, metallic soaps, and the like. This invention is specifically concerned with the use, as E. P. characterizing ingredients, of compounds new and novel for this purpose, and not heretofore so used or known to be useful for this purpose.

It is an object of this invention to provide an extreme pressure lubricant, which lubricant is superior to lubricants of this class heretofore commonly known, particularly in load-carrying capacity, stability, and maintenance of extreme pressure lubricating properties under sustained conditions of high loading, It is an object of this invention to prepare novel and valuable ingredients and to combine them with hydrocarbon lubricant oils to produce lubricants having high load bearing capabilities, to prepare such ingredients which have good characteristics of stability, which are less corrosive, and which impart a greater influence when present in much smaller amounts than are required with extreme pressure ingredients now commercially available. Further objects are the provision of methods of making the ingredient or ingredients, methods of preparing lubricants containing these novel characterizing ingredients, and methods of lubrication making use of the lubricants so produced.

It is an important object of this invention to provide means for satisfactorily inhibiting or preventing corrosion from taking place to a serious degreeparticularly in oils of relatively high viscosity index. It is also an object of this invention to alter or modify a highly refined motor oil, normally corrosive, by the use of additive ingredient capable of substantially inhibiting this corrosion. It is a further object of this invention to provide a substantially noncorrosive motor oil of high V. I. Still another object of this invention is to provide an additive reagent or ingredient capable of inhibiting the corrosive properties of these oils. The production of solvent refined oils of low corrosive prop erties under. conditions of automotive use is: a maior'object of this invention, as well as the. method of production of such oils which comblue a relatively high viscosity index with a relatively low tendency to produce such corrosion.

A further object of this invention is the provislon of lubricating oils, particularly oils for use in internal combustion engines, which do not deposit gummy or resinous films or -lacquers upon pistons, rings, valves, and cylinder walls of engines, and especially thoseoperated at relatively high temperatures and/or for long periods of time.

I have found that hydrocarbon oils of the classes defined above can be stabilized against the formation of acidic and/or corrosive and/or sludge bodies by the addition to said oils of a relatively small amount of a substantially stable, oil-soluble, water-insoluble reaction prodnot of an ester of phosphorous acid and an alkyl aroxy alkanol. I have also found that novel lubricants having extreme pressure lubricating characteristics can be produced by adding to oil a suflicient' quantity of said reaction product. Among the esters of phosphorous acid which may be suitably employed in the production of my reaction products are the aryl phosphites such as triphenyl phosphite, trinaphthyl phosphite, trianthryl phosphite; the alkylated aryl phosphites such as the tricresyl phosphites, trixylenyl phosphites, triethyl phenyl phosphites, tripropyl phenyl phosphites, tributyl phenyl phosphites, triamyl phenyl phosphites, and the isomers and higher homologues thereof. While I prefer to employ the aryl phosphites in the production of my reaction products, I may also utilize the alkyl phosphites such as trimethyl hosphite, triethyl phosphite, tributyl phosphite, triamyl phosphite, and the like. Mixed alkylaryl phosphites and hydro-aromatic phosphites, as well as aryl or alkyl mono and diphosphites and the esters of hypophosphorous, pyrophosphorous, and thiophosphorous acids may also be employed.

The substituted alkanols which I utilize in the preparation of my reaction products are preferably the alkylaroxy alkanols having the general formula R.C1:H2na:-O.R'.OH, wherein R" comprises hydrogen or one or more alkyl or substituted alkyl groups, preferably alkyl groups substituted alkanols are phenoxymethanol, propyl phenoxymethanol, butyl phenoxymethanol, amyl phenoxymethanol, hexyl phenoxymethanol, heptyl phenoxymethanol, and the higher homologues decyl, lauryl, cetyl,'oleyl, and stearyl phenoxymethanols. In lieu of the phenoxy group, other aroxy groups such as naphthoxy and anthroxy may be utilized, and in lieu of the methanol group, other alkanol groups such as ethanol, propanol, butanol, pentanol, and the like may be used. The substituted alkyl group R and the substituted methylene group R' may contain as substituents halogen and/or sulfur.

The above mentioned substantially stable oilsoluble, water-insoluble reaction products are adapted, as I have discovered, to be added directly to or dissolved in a hydrocarbon oil for the purpose of inhibiting or eliminating the normal tendency of said oils t corrode'the metal bearings and parts hereinbefore mentioned, to stabilize said oils against the accelerating action of metals on the deteriorating eflects of oxidation reactions under normal conditions of use and/or handling and/0r storage and to increase the ability of the oil to withstand high unit loadings. By substantially stable, I mean stable under the normal conditions of use and/or handling and/or storage to which these corrosion inhibitors and oxidation inhibitors are ordinarily subjected, after manufacture, either qualities it is desired to impart to the oil.

before they are added to the hydrocarbon oil to be stabilized or after they are added to such an oil.

In preparing the reaction product to be employed in accordance with my invention, I prefer to admix the ester of phosphorous acid with the .alkyl aroxy alkanol and thereafter bring the mixture to a temperature sufiicient to cause reaction of the ingredients, whereby there is introduced into the ester of phosphorous acid at least. one alkyl aroxy alkanol group. The mol ratio of ester to alkanol employed may vary from about 1: 1 to about 122.5, and is preferably of the order of about 1: 14. The admixture of ester and alkanol may be heated at atmospheric pressure under a reflux condenser to a temperature sufficient to efiect reaction, for example, temperatures of the order of from about 200 F. to about 500 F., and the resulting oil-soluble, water-insoluble reaction product may be separated from the byproducts of the reaction by distillation under reduced pressure, or by recrystallization from a suitable solvent, or by washing with a solvent having selective solvent power for either the reaction. product or the undesirable byproducts. Or, if the ester and the alkanol are relatively high boiling, the reaction may be carried on at efevated temperatures of the order of from about 200 F. to about 350 F., under reduced pressures of the order of m. m. or less. On the other hand, if the ester and the alkanol are not relatively high boiling,

the reaction may be carried on at elevatedtemperature and under a suitable superatmospheric pressure. Depending uponthe ratio of ester to alkanol employed, and upon the temperature and time of reaction, at least one and in some instances two alkanol groups may be introduced into the ester of phosphorous acid. In general, it is preferred that the alkyl aroxy alkanol have a boiling point higher than that of the alcohol or phenol employed initially in the manufacture of the ester of phosphorous acid. The reaction products so produced may be regarded as Complex esters of phosphorous acid which may or may not contain unreacted alkanol. Such reaction products have a wider range of utility, and effectiveness as-inhibitors and the like than the simple esters from which they are prepared.

Alternatively, my reaction product may be produced directly in hydrocarbon oil by adding thereto suitable quantities of ester and alkanol, and then heating the mixture to a temperature sufiicient to cause the reaction of the ester with the alkanol, undesirable byproducts of the reaction being removed by distillation or by washing With a suitable solvent.

The reaction products produced in accordance with my invention may be added to hydrocarbon oils in varying amounts, depending upon the For example, in order to inhibit oxidation of hydrocarbon oils such as lubricating oil, turbine oil, or electrical insulating oil such as transformer or cable oil, I may incorporate in the oil from about 0.05% to about 0.5% of my reaction'products. In the case of lubricating oils for internal combustion engines, quantities of reaction product of the. order of 0.1% to about 0.7% will inhibit the formation of color bodies andacidity, and will inhibit corrosion of bearing metals such as cadmium-silver and copper-lead alloys. My reaction products, when employed in quantities of the order of 0.4% to about 0.7%,will inhibit the formation of sludge, resinous bodies, or lacquers, and will impart to the oils moderate, degree of film strength or extreme pressure characteristics. Where a considerable degree of improvement in film strength or extreme pressure characteristics is required, my products may be employed in amounts of the order of 1% to 2%, or more. In those cases where it is desirable, from an economic point of view, to employ only sufiicient quantities of my reaction products to inhibit oxidation of the oil, and to obtain a high degree of film strength by the .addition of other agents, I may-add to the oil, for example, 0.4% of my reaction products and 0.6% of a film strength agent such as tricresyl phosphate. Other film strength agents, of course, may be employed in lieu of or in addition to tricresyl phosphate, and the quantities of such agents may be varied, as desired.

The reaction products of my invention may be utilized not only as inhibitors or film strength agents for hydrocarbon oils, but also for similar a relatively large proportion of a refined hydrocarbon oil normally tending to deteriorate by oxidation under normal conditions of use and in intimate admixture therewith a relatively small amount sufficient to inhibit such deterioration, of an oil-soluble, water-insoluble mixed ester produced by the reaction of an ester of phosphorous acid and an alkyl aroxy alkanol.

2. A hydrocarbon oil composition comprising a relatively large proportion of a refined hydrocarbon oil normally tending to deteriorate by oxidation under normal conditions of use and in intimate admixture therewith a relatively small amount sufficient to inhibit such deterioration, of an oil-soluble, water-insoluble mixed ester produced by the reaction of an aryl ester of phosphorous acid and an alkyl aroxy alkanol.

3. A lubricant comprising hydrocarbon lubricating oil and a small amount of an oilsoluble, water-insoluble mixed ester produced by the reaction of an ester of phosphorous acid and an alkyl aroxy alkanol.

4. A lubricant comprising hydrocarbon lubricating oil and from about 0.05% to about 2.0% of an oil-soluble, water-insoluble mixed ester produced by the reaction of an aryl ester of phosphorous acid and an alkyl aroxy alkanol.

5. A lubricant comprising hydrocarbon lubricating oil and from about 0.4% to about 0.7% of an oil-soluble, water-insoluble mixed ester produced by the reaction of an aryl ester of phosphorous acid and an alkyl aroxy alkanol.

6. The method of lubricating bearing surfaces, which comprises maintaining between bearing surfaces, one of which'is an alloy selected from the class consisting of cadmium-silver, cadmium-nickel, cadmium-zinc, cadmium-zinc-leadantimony, copper-lead, copper-lead-tin, and high lead babbitts a film of lubricating oil which initially produces an effectivelubricating action but which would normally tend to corrode the aforesaid alloy, and maintaining the eflectiveness of the lubricating oil by incorporating thereina small amount, suflicient to substantially retard corrosion, of an oil-soluble, water-insoluble mixed ester produced by the reaction of an ester of phosphorous acid and an alkyl aroxy alkanol.

'7. The method of lubricating bearing surfaces which'comprises maintaining between bearing the class consisting of cadmium-silver, cadmium-nickel, cadmium-zinc, cadmium-zinc-leadantimony, copper-lead, copper-iead-tin, and

7 high lead babbitts, a film of lubricating oil which initially produces an efl'ectivealubricating action but which would normally tend to corrode the aforesaid alloy, and maintaining the effective- CERTIFICATE OF CORRECTION.

Patent No. 2,525,076.

RAYMOND REUTER.

It is hereby'certified that error appears in the printed specification of the above numbered. patent requiring correction as follows: Page 1, first column, line 14., for "of" before "petroleum read --to--; and that the said Letters fatent should be read with this correction therein that the same may eonfom to the record of the case in the- Patent Office.

Signed and sealed this 5th day of October, A. D. 19%.

(seal) Henry Van Arsdale,

Acting Commissioner of Patents.

. CERTIFICATE OF conmzcnou. Pste t No. 2,325,076, July 27, 191+ .mmoma REUTER.

It is hereby certified that error appears in the printed specification or the above numbered pstent requiring correction as follows: Page 1 first column, line 14., for "of" before "petroleum" read --to--; and that the said Letters fatent should be read with this correction therein that the same may eonform to .the record of the case in the- Patent Office.

Signed and sealed this th da of October, 1). 19M.

Henry vn Arsdale, (Seal) Acting Commissioner of Patents. 

